A General Analytical Integration of Reinforced Concrete Sections subject to Axial Force and Biaxial Bending

This paper presents a general analytical integration for the evaluation of section resistant forces and tangent modulus of arbitrary polygonal reinforced concrete sections subjected to axial force and biaxial bending, no matter what kind of stress-strain relationship is supposed. Through the definition of several concrete constitutive integral functions which are only dependent on the constitutive law equation, both the inner forces and the sectional tangent modulus matrix can be calculated through analytical equations. Nonlinear analysis of a cantilever was also conducted to verify its exactness, in which the section properties at the numerical integration point are according to equations presented in this paper, and very good results were provided.